d and f BLOCK ELEMENTS

Which of the following best describes the electronic configuration of a neutral Lanthanoid atom?

• [Xe] 4fⁿ 5d⁰⁻¹ 6s²
• [Xe] 4fⁿ 6s² 6p⁶
• [Xe] 5dⁿ 6s²
• [Ar] 3d¹⁰ 4s²

What is the primary reason for the difficulty in separating Zr and Hf, according to the text?

• Their almost identical ionic/atomic radii
• They form identical compounds
• They have the same atomic number
• They are both radioactive

Which of the following best describes the relationship between the lanthanoid contraction and the shielding effect?

• The lanthanoid contraction is caused by the imperfect shielding of 4f electrons
• The lanthanoid contraction is caused by perfect shielding of 4f electrons
• The lanthanoid contraction increases shielding effectiveness
• The lanthanoid contraction is unrelated to shielding

What is the approximate ionic radius of Zirconium (Zr) in picometers, as mentioned in the text?

• 160 pm
• 140 pm
• 180 pm
• 150 pm

What is the approximate ionic radius of Hafnium (Hf) in picometers, as mentioned in the text?

• 159 pm
• 145 pm
• 175 pm
• 130 pm